Ugh, what the hell people? You're all getting this wrong.
First of all, that info came straight from the site owner, reidman. Who got the info from a source he didn't reveal. On the staff forums, he also told them, beforehand, that the Franklin Badge was going to be an item and the exact date it was going to be confirmed. I highly doubt he would ever dare to lie at all, period, or spread some type of trickery. He really isn't the type of person to do that.
Yes, he is telling the truth. However, he didn't say that Lucas was going to be the only main Mother character in Brawl, he said that Lucas was going to be ONE of the main characters in Brawl, which means he'd basically be default.